The current language of the bill — which is in its early form — would allow for either a so-called “resource officer” (essentially an armed police officer, the kind which most Tennessee high schools have already) or an armed member of the faculty or staff in every school in the state. The choice would allow schools that can’t afford a resource officer to fulfill the requirement without having to pay for anything beyond the cost of the training and, presumably, the weapon. But Niceley said schools should use the wiggle room to train and keep on hand armed staff not in uniform.

[Gov. Bob McDonnell], a Republican, said during his monthly radio show on Washington’s WTOP on Tuesday that if school officials were trained and chose to have a weapon, they might have an opportunity to stop someone from trying to get into a school.

“I know there’s been a knee-jerk reaction against that. I think there should at least be a discussion of that,” Mr. McDonnell said. “If people were armed, not just a police officer, but other school officials that were trained and chose to have a weapon, certainly there’d be an opportunity to stop aggressors coming into the schools.”

Here's the problem: for something like this, you need a perfect safety system. Laws and regulations, and human and institutional behavior must be flawless. The vast majority of school employees trained in gun use will of course behave responsibly. But some won't. And when even one fails to secure his/her weapon, or pulls it out in anger, or ... ? you've suddenly got a very dangerous situation. Also, a gun must be in a place where a students can never access it, but the school employee must be able to access it instantly, in an emergency. Alternatively, if a teacher is carrying, what happens if she/he gets into an altercation with a student? More generally, can some set of rules be devised that eliminate the chance of something going wrong? Because the chances of that happening are far greater than an attack by someone bent on mass murder.